Prior U.S. Pat. No. 3,911,160, which was granted to co-inventor William B. Neuberg, describes a method for curing solvent free inks by the application of a powder resin to a freshly printed surface. The printed surface then cured, such as by passing it through a heating apparatus, wherein the resin melts, curing the ink.
The prior patent suggests mechanically leveling the printed surface following curing to produce a high gloss. Applicants have found that in some instances such mechanical leveling causes a smearing of the ink and molten powder resin coating, particularly on printed surfaces using half-tone dots. Such mechanical leveling can cause a smearing of the half-tone dots to an oval or teardrop shape without producing a uniform coating surface.
The present invention is an improved method of using resin powders to cure solvent free inks and provides a process wherein high gloss can be achieved with a half-tone printing process and without the use of a mechanically leveling apparatus that would produce smearing of the half-tone dots. The process permits replication of the high gloss or matte caulstock, or other release surfaces described herein, and eliminates the problem of smearing of the molten powder resin coating or half-tone dots experienced in the earlier patent.